Marx's Theories of Surplus Value is the fourth volume of his monumental Das Kapital (Capital) and is now available exclusively from Prometheus and Humanity Books. Divided into three parts, this lengthy work reviews classic economic analyses of labor and value (Smith, Ricardo, Malthus, and others), focusing on the concept of "surplus value"—the difference between the full value of a worker's labor and the wages received for this labor. This is a key concept for Marx since in his view the capitalist maintains power through controlling surplus value. This complete, unabridged edition is now available in one volume.